Laser diodes emit light when current is passed through the diode. The output luminance of the laser diode varies as the drive current through the diode is varied. The output luminance of the laser diode may also vary due to other factors. For example, the output luminance of the laser diode may vary with age. Also for example, the output luminance of the laser diode may vary as the temperature of the diode varies. This can be problematic in part because the temperature of a laser diode may be affected by ambient temperature changes as well as the historical drive current which results in “self-heating” of the diode.
Laser projectors that utilize laser diodes for light generation may suffer from variations in luminance as a result of aging, temperature changes, and other factors. These problems may occur in both monochrome and color laser projectors. For example, monochrome laser projectors may suffer from non-uniform greyscale displays over time. Similarly, the luminance of the various colors in a displayed image may change as the luminance of each color laser diode in a color projector changes. The color balance may also be affected if different color laser diodes have different responses to factors that affect luminance (e.g., aging, temperature, etc.).